ANAT241 L1 Flashcards
What are 3 characteristics of the basic structure of a human cell?
- Bound by plasma membrane
- Contains cytoplasm
- Contains organelles
What are 2 components of cytoplasm, of a human cell?
- viscous fluid
- filaments and fibres forming cytoskeleton
What is viscous fluid otherwise known as?
cytosol
What are 2 components of organelles, of a human cell?
- membrane and non-membrane bound
- includes nucleus (control centre, houses DNA)
What are 2 components of the nucleus?
- control centre
houses DNA
What are cells surrounded by?
The plasma membrane
What is the purpose of the plasma membrane?
Separate the inside of the cell from the outside environment
What is a plasma membrane?
A semi-permeable, selective barrier
The plasma membrane surrounds the cells. What does it also surround?
Membrane-bound organelles
What is a plasma membrane?
Dynamic
What are the 3 key components of the plasma membrane?
- phospholipids
- cholesterol
- proteins
What are the 3 key functions of the plasma membrane?
- Protection
- Transport
- Communication
What are proteins essential for?
Cell function
What are the 2 groups of membrane proteins?
Integral and peripheral
What are some characteristics of integral membrane proteins?
- Anchored to membrane
- Some part way
- Some span entire membrane
What is the name for integral membrane proteins that span the entire membrane?
Transmembrane proteins
What are some characteristics of peripheral membrane proteins?
- on the outside or inside of membranes
- may be attached to integral proteins, or phospholipids
What do cells need in order to know what to do?
Signals
Where do most signals come from?
Outside the cell
What are the 3 ways a signal can get to a cell?
- diffuse across plasma membrane
- enter through channels or carriers
- they don’t
How does a signal reach a cell, through: diffusing across the plasma membrane?
small lipophilic molecules (e.g. gases, vitamins, steroid hormones)
How does a signal reach a cell, through: entering through channels or carriers?
small molecules (e.g. Ca2?, thyroid hormone)
What happens to a signal for it to NOT reach the cell?
- receptors bind a ligand outside the cell
- signal transducer inside the cell
- causes a cellular reaction
What are the 2 key function of the skeleton?
help maintain cell shape and structure
What is the cytoskeleton essential for?
- cell division
- cell movement
- vesicle movement within cells
What is a cytoskeleton?
dynamic - it changes to meet the needs of the cell
What are the 2 key functions of a microtubule?
- resist compression
- help maintain cell shape
What are microtubules important for and how?
- motility
- form flagella and cilia, organelle motility
What are the 2 key functions of microfilaments?
- resist tension
- form cortical network beneath plasma membrane
What are microfilaments important for and how?
- movement
- actin and myosin interactions for muscle contraction
What are the 2 key functions of intermediate filaments?
- form more permanent structures
- anchor organelles
What are intermediate filaments important for and some examples of it?
- cell adhesion
- cytokeratin, neruofilaments, lamina
What are organelles?
sub cellular structures with specific functions
What are 2 key functions of organelles?
- often membrane-bound
- create defined areas and environments within the cell
What are 3 examples of 3 key organelles?
- nucleus
- endomembrane system (endoplasmic reticulum, Golgi, vesicles)
- mitochondria
What is the mitochondria?
the site of cellular respiration
What are 2 key characteristics of the mitochondria?
- double membrane structure
- number per cell depends on energy demands
What is the key function of the mitochondria?
generate energy
How does the mitochondria generate energy?
- consume glucose and oxygen
- produce CO2, water and energy: ATP
What is the nucleus?
the control centre of the cell
How many nuclei are normally found per cell?
one
What are features that the nucleus contains?
- contains most of the cells DNA (eurochromatin & heterochromatin)
- contains nucleolus (makes rRNA & ribosomal subunits)
What are 2 structural features of the nucleus?
- surrounded by nuclear envelope (double membrane, continuous with ER)
- inner surface lined with nuclear lamina
What is a nuclear envelope?
What is the nuclear envelope spanned by?
nuclear pores
What is the process of a nuclear envelope being spanned by nuclear pores?
- channel made of nucleoporins
- ## allows mRNA, tRNA and ribosomal subunits to move to cyotoplasm
What does the nuclear envelope being spanned by nuclear pores allow?
- allows mRNA, tRNA and ribosomal subunits to move to cyotoplasm
- allows building materials, energy and control signals into nucleus
What is the endomembrane system?
an interconnected system
The endomembrane system is an interconnected system that includes what?
- endoplasmic reticulum (ER)
- golgi apparatus
- vesicles
What is the function of the membrane system?
modify, package and move protein & lipids
What are the 2 types of endoplasmic reticulum?
- smooth ER
- rough ER
What is a characteristic of the smooth ER?
- lacks ribosomes on surface
What are 4 of the key functions of a smooth ER?
- synthesise lipids
- metabolise carbohydrates
- detoxification processes
- store calcium ions
Of the smooth ER, what are the store calcium ions used as?
a signal within the cell
What is a characteristic of the rough ER?
covered with ribosomes on outer surface
What is the key function of the rough ER?
its role in protein synthesis
What is the rough ER’s role in protein synthesis?
- proteins enter lumen of rER
- proteins are modified, folded and packaged into vesicles
- transported to Golgi
What is the Golgi apparatus/complex?
a series of membrane sacs and vesicles
What is the role of the Golgi apparatus/complex?
- vesicles from ER arrive at cis face
- proteins modified, glycosylated, sorted into vesicles
- vesicles leave from trans face
What are 2 features of a vesicle?
- membrane bound
- move via motor proteins ‘waling’ along microtubules
What are the 2 types of vesicles?
- transport vesicles
- secretory vesicles
What is the role of transport vesicles?
move contents WITHIN cell
What is the role of secretory vesicles?
move contents OUT of cell
What is the process where secretory move contents out of the cell called?
exocytosis
Secretory vesicles are how most contents are moved out of the cell. What molecules are released during this process?
how most signalling molecules are released
Why do cells need to communicate?
- send and receive instructions
- coordinate functions
What would happen if there were no cell-to-cell communication (cell signalling)?
there would be no functionality of cells, tissues and organs
Cell signalling is a multi-step process, what does this process involve?
-sending, and reception, of signal
- then changes inside the cell which impacts the amount or activity of specific proteins
In a general sense, what is cell signalling and what does it do?
- a complex system of communications
- controls all cellular function
Cell signalling impacts the amount/activity of a specific proteins, how so?
- alter gene expression for a specific protein
- alter activity of a specific protein
What are the 3 key functions of cell signalling?
- receive signal
- transduce signal
- respond to signal
What is the multi-step process of cell signalling?
- synthesis of signal molecule
- release of signal molecule
- transport of signal molecule to target
- detection of signals by target cell (reception)
- response by large cell
- feedback
What must be considered, during the multi-step process, of cell signalling?
- sending the message (what the signal molecule is, how it will reach the target cell and how it will deliver the message to the right place)
- what happens after the signal is received (what pathways are activated inside the cell and what the outcome is)
- what happens when things go wrong
